GB2093954A - Filling nozzle structure - Google Patents

Abstract

A filling nozzle structure 10 for use with filling units with suction and discharge strokes includes an elastic sleeve-like member 40 which, in the absence of discharge pressure at the nozzle structure inlet bore 31, closes off communication between the bore 31 at a valve body 21 to a recess 13 within a nozzle body 12. The sleeve- like member 40 when acted upon by the discharge pressure of the filling product in the bore 31 is distended and thereby opens up the communication through bores 24. Upon disappearance of the discharge pressure, the member 40 collapses again thereby closing off such communication and producing a suction effect by the formation of a suction chamber 60a between its external surfaces and the internal surfaces of the recess 13. Thus product in the nozzle outlet bore 14 communicating with the recess 13 is sucked back at each suction stroke of the filling unit. <IMAGE>

Description

SPECIFICATION Filling nozzle structure The present invention relates to a filling nozzle structure, and more particuiarly to a filling nozzle structure for use with piston-type filling units of filling machines.

In filling machines of the type described in the U.S. Patents 2,807,213 and 3,237,661, each piston-type filling unit as described, for instance, in U.S. Patents 2,807,213 and 2,907,614, has a suction stroke and a discharge or power stroke and is connected with a respective filling nozzle by way of a hose. In these prior art filling machines, the filling nozzles are lowered into containers to be filled; the product with which the containers are to be filled is then discharged under pressure into the containers during the power stroke of the filling units, and the nozzles are thereafter raised out of the containers during the next suction stroke.To provide proper operation, a valve assembly is normally included in a respective filling unit and, during the power stroke of the filling unit, closes the supply of feed line to the piston pump of the filling unit while opening the discharge line to the filling nozzle, and during the suction stroke closes the discharge line leading to the filling nozzle while opening the feed line to permit a fresh supply of product to be sucked into the piston pump of the filling unit for discharge thereof during the next power stroke.

Valve assemblies of this type are described, for example, in U.S. Patents 2,807,213; 2,978,149 and 4,055,281 (British Patent No. 1565070).

To prevent spillage of small quantities of the filling product which may be left behind in the nozzle discharge bore and which otherwise may drop onto the conveyor or onto the outside of the containers after the discharge stroke is completed and after the nozzles have been raised out of the containers, so-called suck-back devices have been used heretofore as disclosed, for example, in the U.S. Patents 2,978,149 and 3,771,908.

Though these prior art suck-back devices proved quite successful, they entail certain drawbacks.

More specifically, they require structural changes which not only increase the cost of manufacture, but also require adjustments. An adjustable suckback arrangement is also described in U.K. Patent Application Publication 2037881 A.

It is therefore a principal object of the present invention to provide a suck-back device in a filling nozzle structure which is simple in construction, relatively inexpensive to manufacture and reliable in operation without the need for any adjustments.

The prior art suck-back devices are located in or associated with the valve assembly of the filling unit and are therefore located from the nozzle structure by a distance substantially the length of the connecting hose. By providing the suck-back device relatively close to the discharge end, i.e. in the nozzle structure, after-dripping can be reliably precluded by simple means that need produce only a relatively slight amount of suction.

In a preferred embodiment of the present invention, the filling nozzle structure, which consists of several parts adapted to be assembled together, forms a recess that accommodates a valve so constructed and arranged that its actuation by the discharge pressure of the filling product causes the valve to open, thereby reducing the effective volume of a chamber formed between the external surfaces of the valve and the inner surfaces of the recess, a suction effect being produced when the valve again automatically closes upon disappearance of the discharge pressure of the filling product as a result of the reappearance and/or increase in volume of this chamber.In one particulariy simple construction, this valve has a tubular, sleeve-like member of any suitable elastic plastic material, for example, silicone rubber, which is stretched over a valve body so as to normally close off the nozzle inlet bore within the valve body with respect to the recess accommodating the valve body, whereby the discharge pressure of the filling product will cause the elastic tubular member to expand generally radially toward the internal recess walls which in turn causes an effective reduction in the volume of the chamber formed between the external surfaces of the sleeve-like member and the internal walls of the recess during the power stroke of the filling unit.

Upon completion of the power stroke, the sleevelike elastic member will again collapse as a result of the disappearance of the discharge pressure of the filling product, which causes an increase in the volume of the chamber, thereby producing a suction effect within the discharge bore of the filling nozzle itself A preferred filling nozzle structure embodying the present invention consists of only four parts, of which three can be readily manufactured, for example, by machining, injection moulding or any other known technique while the fourth part, the elastic, sleeve-like member, merely represents a piece of tubular hose-like section cut off from commercially available stock, whereby the various parts are so constructed that they can be easily assembled and disassembled for servicing, for example, for cleaning or replacement of the sleeve-like member if necessary.On the other hand, the first three parts not only hold fast the sleeve-like member, but ensure reliable assembly of the filling nozzle structure.

The invention will now be described in more detail, solely by way of example, with reference to the accompanying drawings in which: Figure 1 is an elevational view of a filling nozzle structure embodying the present invention; Figure 2 is an enlarged view, partially in axial cross section, of the filling nozzle structure of Figure 1, showing the parts thereof in a nondischarging condition; Figure 3 is a transverse cross-sectional view, taken along line II I-Ill of Figure 2; Figure 4 is a view, partly in cross section, similar to Figure 2, and showing the parts thereof in the presence of a product under pressure supplied during the power stroke of a filling unit; and Figure 5 is a transverse cross-sectional view, taken along line V-V of Figure 4.

In the drawings there is shown a filling nozzle structure embodying the present invention and generally designated by reference numeral 10.

The nozzle structure 10 includes a relatively long tubular filling nozzle portion 11 of relatively small outer diameter adapted to be lowered into a respective container (not shown) and having a discharge bore 14 which is in communication with a bore 13 forming a recess in a nozzle housing portion 12 by way of a bore 15 of somewhat smaller diameter than the bore 14. A countersunk surface 1 6 connects the bore 1 5 with the recess bore 13 in the nozzle housing portion 12 where an internal chamber with varying volume is formed within the recess bore 13 as will be described more fully hereinafter. As can be seen from Figure 2, the internal cylindrical surface of the recess bore 13 terminates at a flared surface 17 that defines a receiving opening in the upper end face of the nozzle housing 12 as viewed in Figure 2.

Threads 1 8 are cut into the external cylindrical surfaces of the nozzle housing portion 12 to threadably receive an internally screw threaded nut 50. The nozzle portion 11 and the housing portion 12 are integral with one another The filling nozzle structure includes a valve body 20 that consists of a main body portion 21 adjoined by a stem-like connecting portion 22 on the top thereof and by a head portion 23 on the bottom thereof which closes off an axial bore 31 which is a dead-end bore extending from the open end of the stem-like connecting portion 22 to the closed-off end within the head portion 23.

Radially directed bores 24 provide communication between the axial bore 31 and the recess bore 13. The head portion 23 has a bevel end surface 25 inclined in a complementary manner to the bevel surface 16 so as to provide an annular passage of uniform cross section when the parts are in the assembled condition. A reduced neck portion 26 adjoins the cylindrical part of the head portion 23 by way of an inclined shoulder 27. The reduced neck portion 26 meets a conical surface 28 of the main valve body portion 21 which subtends an angle similar to that of the bevel surface 17 so that in the assembled condition the surface 17 and the surface 28 are substantially parallel and form clamping surfaces. An oppositely sloping conical undercut surface 29 leads from the external conical surface 28 to an annular abutment collar or end portion 30.

The automatic valving action is realized by a sleeve-like tubular member 40 (Figure 2) which is cut off to proper length from a suitable hose material of uniform, appropriate cross section and made from any suitable elastic plastics material, such as silicone rubber. Due to the elastic nature of the sleeve-like member 40 and the fact that it is of smaller diametric dimension in the unstressed condition than any of the diametric dimensions of the valve body 20, the sleeve-like member 40 will generally conform to the external configuration of the valve body 20 when the nozzle is in the non-discharging condition, i.e., when any product in inlet bore 31 and bores 24 is not under discharge pressure.In this unstressed condition, the sleeve-like member 40 includes a lower end portion 41 securely resting on the cylindrical surfaces of the valve head portion 23, which, in the upward direction, joins with a neck portion 42 of reduced diameter which closes off the radially directed bores 24. The frusto-conical portion 43 of the sleeve-like member 40 which adjoins the neck portion 42, is clamped-in between the surfaces 1 7 and 28 when the nut 50 is screwed over the external thread 1 8. An upper end portion 44 of the member 40 grips the short conical surface 29.

The nut 50 is provided with an annular shoulder 51 which engages the collar portion 30 of the valve body 20. When the nut 50 is screwed over the threaded portion 1 8 of the nozzle housing portion 12, its shoulder 51 abutting against collar 30 urges the valve body 20 downwards, thereby producing a clamping action on the frusto-conical portion 43 of the sleeve-like member 40 between the conical surfaces 1 7 and 28.

The operation of the suck-back filling noule structure shown in the drawings is as follows: During the period of time when product is not under discharge pressure in inlet bore 31, i.e., during the suction stroke of a filling unit (not shown), the parts of the filling nozzle structure are in the positions illustrated in Figures 2 and 3, in which the sleeve-like member 40 conforms generally to the configuration of the valve body 20, thereby closing off the radially directed bores 24 and forming a chamber 60a between its outer surfaces and the internal cylindrical surfaces of the recess bore 13.

If a product under discharge pressure is now supplied to the inlet bore 31, the pressure thereof will cause the sleeve-like member 40 to lift off the valve body 20 as shown in Figures 4 and 5 to provide a passage for the product under discharge pressure from the inlet bore 31 to the discharge bore 14 by way of the chamber 60b now formed between the external surfaces of the valve body 20 and the internal surfaces of the sleeve-like member 40, the annular passage between bevel surfaces 16 and 25 and the connecting bore 15.

The sleeve-like member 40 will then tend to press against the cylindrical surfaces of the recess 1 3 until such time as the disappearance of the discharge pressure during the suction stroke of the filling unit will cause the sleeve-like member 40 to collapse again as shown in Figures 2 and 3.

This will not only cause the closing of the bores 24 and the disappearance of the chamber 60b, but will also cause reappearance of the chamber 60a, which produces a suction effect within bores 14 and 1 5 since the bores 24 are closed off as soon as the portion 41 of the member 40 grips the valve head portion 23.In other words, the sleeve-like member 40 acts in the manner of a diaphragm by closing off the holes 24 and effectively forming the suction chamber 60a which will prevent with certainty the afterdripping of any product that may have remained within bore 14 and/or bore 1 5. The suction effect is produced primarily by contraction of the neck portion 42 of the member 40 through the annular volume between the outer surfaces 27, 26 and part of 28, on the one hand, and an imaginary upward continuation of the cylindrical surface of the cylindrical part of the head portion 23, on the other.

When the chamber 60b collapses during the suction stroke of the filling unit, the product occuping this chamber is forced back towards the filling unit, while the product in the bores 14 and 1 5 is drawn back to the suction chamber 60a being formed. No product is expelled during the collapse of the chamber 60b. The hose (not shown) connecting the stem-like connecting portion 22 of the nozzle structure to the outlet port of the filling unit (not shown) must provide unobstructed passage between the filling unit and the axial bore 31 of the connecting portion 22 and in particular must not include a check valve, otherwise the sleeve-like member 40 will not collapse during the suction stroke.

The filling nozzle structure described is thus simple, requires very few parts, can be easily assembled and disassembled and readily serviced. Moreover, the valving and suck-back effect produced by the sleeve-like member 40 is highly effective due to the fact that the suction chamber 60a is located in close proximity to the discharge bores 14 and 1 5.

The nut 50 can be replaced by any other fastening means and can be eliminated altogether if the valve body 20 is provided with an external threaded portion of sufficient length, for instance, in the region of the collar 30, adapted to be screwed into an internally threaded part in the upper end area of the housing portion 12, whereby the nozzle structure would require only three parts, namely, the housing portion 12 with filling nozzle portion 11, the valve body 20 and the elastic sleeve-like member 40.

As described hereinbefore, when the chamber 60b collapses during the suction stroke of the filling unit, any product in the chamber 60b is sucked back towards the filling unit while the product in the bores 14 and 1 5 is drawn back to the suction chamber 60a being formed. Collapse of the chamber 60b precludes discharge of product through the bores 14 and 15. Slnce the nozzle structure itself thus performs a valving function, the connecting portion 22 can be connected directly to the outlet port of a pistontype filling unit (not shown) without interposition of a valve. In other words, the filling unit does not require a valve at its outlet port since the valving function at the discharge side of the unit is performed by the filling nozzle structure embodying the invention.

The invention will now be described in more general terms in the following claims.

Claims (14)

Claims

1. A filling nozzle structure which includes nozzle body having a discharge end in communication by way of a discharge passage with a recess which is located within the nozzle body and is adapted to be connected through suck-back means to a pressure source for intermittently supplying a filling product under pressure, the suck-back means including within the recess, pressure-actuated valve means operable by the discharge pressure of the filling product and operable by the disappearance of the discharge pressure to selectively produce a suction effect within the discharge passage.

2. A nozzle structure according to claim 1, wherein the valve means includes an elastic member arranged to be acted upon by the discharge pressure of the filling product in such a manner as to be urged toward an internal surface of the said recess in the presence of such pressure and to collapse as a result of its elastic characteristics upon disappearance of the discharge pressure, thereby effectively forming a suction chamber between its exterior and the internal walls of the recess and thus producing a suction effect within the discharge passage.

3. A nozzle structure according to claim 2, wherein the valve means includes a valve body disposed at least partly within the said recess and provided with a dead-end inlet bore adapted to be connected at its open end with the said pressure source and closed at its end nearer the discharge passage, the inlet bore being in communication with the recess by way of communicating bores extending at an angle to the axis of the inlet bore, and the elastic member is a tubular member of elastic material of such diametric dimension and elasticity that it normally presses snugly against outer surfaces of the valve body to close off the communicating bores, the said suction chamber constituting the space between its outer surfaces and internal surfaces of the recess means whereas in the presence of the pressure of the filling product the tubular member lifts away from the valve body to open up the communicating bores and thereby cause a reduction in the volume of the suction chamber, the volume of the suction chamber again increasing upon rapid reduction of the pressure of the filling product thereby producing a suction effect within the discharge passage in communication therewith.

4. A nozzle structure according to claim 3, wherein a plurality of the said communicating bores are provided distributed over the circumference of the valve body and extending generally radially, and, in the presence of the discharge pressure of the filling product, the tubular member distends to press against an internal surface of the recess to cause disappearance of the suction chamber.

5. A nozzle structure according to claim 3 or 4, wherein the valve body and nozzle body are provided with inclined, substantially complementary surfaces between which the tubular member is clamped fast when the nozzle body and the valve body are urged toward one another by fastening means holding the various parts of the nozzle structure in assembled condition.

6. A nozzle structure according to claim 6, wherein the said fastening means includes a nut having a shoulder portion and operable to threadably engage with an external threaded portion of the nozzle body, the shoulder portion engaging with an abutment portion of the valve body so as to urge the complementary surfaces of the valve body and nozzle body toward one another as the nut is screwed over the threaded portion of the nozzle body.

7. A nozzle structurs according to claim 5, wherein the said fastening means includes an externally threaded portion on the valve body for engagement with a complementary internally threaded portion of the nozzle body, the said threaded portions being located within the area of the open end of the said recess.

8. A filling nozzle structure for discharging therethrough a product under pressure into a container, which structure includes a nozzle body having a discharge end that is in communication with a recess, characterized by a normally closed valve means valving the inlet to the recess and including elastic valve closure means operable by the discharge pressure of the filling product to open up a communication with the said recess and operable to produce a suction effect in a diaphragm-like manner upon disappearance of the discharge pressure.

9. A filling nozzle structure according to claim 8, wherein the elastic valve closure means is an elastic, sleeve-like tubular member mounted in stressed condition over a valve body.

10. A filling nozzle structure according to claim 9, wherein the nozzle structure essentially consists only of a unitary nozzle body, the valve body, the elastic, sleeve-like member and a means of fastening to hold the parts in assembled condition.

11. A filling nozzle structure according to claim 10, wherein the said fastening means includes a separate nut-like fastening element operable to exert a force on the valve body when tightened over the nozzle body which force translates itself into a clamping pressure to hold the sleeve-like member in place.

1 2. A filling nozzle structure according to claim 10, wherein the said fastening means are formed by interengaging threaded surfaces of the nozzle body and the valve body.

1 3. A filling nozzle structure according to any one of claims 8 to 11, wherein the nozzle structure is readily detachable and consists at most of four parts adapted to be readily assembled and disassembled.

14. A filling nozzle structure substantially as described hereinbefore with reference to the accompanying drawings.